There are a number of lines in that particular poem that have a line to themselves. Personally I wouldn't refer to them as lines but as layout or format. (That's an uneducated comment. Poetry ain't my strong point.)
However, some standard poems using standard metric foot can accomplish a whole line in a single word.
The metre I'm thinking of is double dactyl. (Dactyl is a long followed by two shorts. A double dactyl does it twice.) In the following poem "incomprehensible" is a double dactyl and, consequently a line, all by itself.
Edward M. Kennedy
Drove in a stream.
Pleas of amnesia